Outdrive - where does it draw water?

Magnus Wallner

Magnus Wallner

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Having read thru the manual I still don't get it...

I have a 1992 Merc 5,7 with Alpha One gen2 and a full closed cooling system. I'm trying to figure out wether the raw water pump feed both the engine and the outdrive with water OR if the raw water pump feeds the engine only and that the pump in the outdrive has its own inlet (and outlet off course).

The reason for me asking is that I want to know what's required if I wanna run the engine on land.


Thanks!
 
F

fmalott

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Re: Outdrive - where does it draw water?

raw water is sucked up from the outdrive then it hits the heat exchanger then get pumped back out the outdrive. when raw water get sucked up to the exchanger that's what cools the antifreese water that circulate threw the engine by the impeller. the antifreese water never leaves the engine
here is a picture where the raw water gets sucked up it also includes the ear muffs you put on the inlet when testing it out on land
 

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Don S

Don S

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Re: Outdrive - where does it draw water?

Do you should have a belt driven raw water pump on the engine itself. It should be located down low on the starboard side of the engine that looks like this.

pump.jpg

If you do, it only feeds the engine from a through hull fitting. The impeller in the drive then just helps cool the drive. and the hose should be cut back between the bellhousing and gimbal housing.

If no belt driven pump on the engine, the drive pump cools everything.
 
Magnus Wallner

Magnus Wallner

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Re: Outdrive - where does it draw water?

I have a separate raw water inlet and pump. Raw water is routed via the pump to the oil cooler and then the heat exchanger. After that it's off to the elbows and presumably then ejected via the exhaust UNLESS it's, and this is my question, going via the pump in the outdrive.

Now I saw the pic, thanks.
 
Magnus Wallner

Magnus Wallner

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Re: Outdrive - where does it draw water?

Don S said:
Do you should have a belt driven raw water pump on the engine itself. It should be located down low on the starboard side of the engine that looks like this.

View attachment 172518

If you do, it only feeds the engine from a through hull fitting. The impeller in the drive then just helps cool the drive. and the hose should be cut back between the bellhousing and gimbal housing.

If no belt driven pump on the engine, the drive pump cools everything.
Click to expand...

Thanks. That's how my pump looks like.

And here's what fell out of the oil cooler 10 minutes ago when I decided to drain the engine from sea water.
bild-1.JPG

One piece is cast metal (the others are impeller rubber) and presumably a piece of the housing so it looks like I'll be replacing the entire pump. Can it be removed from the bracket without falling apart or should I remove the entire bracket with the pump attached?
 
Don S

Don S

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Re: Outdrive - where does it draw water?

Here is the flow diagram for your engine. It should help you understand the engine cooling.

Untitled3.jpg

The engine cooling system has nothing to do with the outdrive, except that the water will exit through the outdrive and out through the prop. The impeller in the drive, only helps cool the drive.
 
Don S

Don S

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Re: Outdrive - where does it draw water?

Magnus Wallner said:
Can it be removed from the bracket without falling apart or should I remove the entire bracket with the pump attached?
Click to expand...

It's easiest to remove the pump and the bracket as an assembly. Then change the bracket to the new pump and re- install.
 
Magnus Wallner

Magnus Wallner

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Re: Outdrive - where does it draw water?

Don S said:
Here is the flow diagram for your engine. It should help you understand the engine cooling.

View attachment 172520

The engine cooling system has nothing to do with the outdrive, except that the water will exit through the outdrive and out through the prop. The impeller in the drive, only helps cool the drive.
Click to expand...

I saw that pic in the manual, I just wasn't sure where the "used" sea water went.
 
Fishermark

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Re: Outdrive - where does it draw water?

Magnus Wallner said:
The reason for me asking is that I want to know what's required if I wanna run the engine on land.
Click to expand...

Do you know if you also have a pump in the lower unit of the outdrive? Since you have the engine mounted pump your may or may not have the pump in the drive as well. There are a few ways of dealing with the extra pump.... sometimes the water hose in the outdrive is simply cut off... sometimes it is routed into and out of the transom... sometimes the impeller is removed completely from the outdrive.

Bottom line is you have to provide water to whatever pump(s) you have.

I had a similar setup in my Sportcraft. I used muffs on the outdrive and stuck a hose in the strainer basket (which you may or may not have).

DSCF1149.jpg
 
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